监听文件变化、python和GIL

zhu894532094

　　1、利用windows api对文件系统进行监听
　　尝试1：利用FindFirstChangeNotificationA、WaitForMultipleObjects、FindNextChangeNotification组合
　　这一组合缺点是就api而言无法获取变更的文件名，还要自己遍历文件夹比对。放弃。
　　尝试2：CreateFileA、ReadDirectoryChangesW组合，完美的组合，可以获取到变更的文件名，唯一不足的是还要用一个函数来转换获取到的文件名(WideCharToMultiByte)。
　　2、关于python调用c语言。使
　　用distutils可以将c程序编译成pyd，然后倒入到python程序中调用。
　　3、由于GIL的关系
　　由于GIL的关系，在调用c程序时，解释器会被锁住，直到c调用结束才释放（也可以自己释放，函数组：PyEval_AcquireLock();PyEval_ReleaseLock();），在监听等待操纵系统通知的时候是阻塞的，锁住之后再被阻塞，程序就不动了，于是便利用popen来调用。在c程序中以printf来与python程序交互。(感谢RednaxelaFX)

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
int main(int argcount, char** args) {
if(argcount != 2){
return EXIT_SUCCESS;
}
char* path = args[1];
HANDLE hDir = CreateFileA(path, FILE_LIST_DIRECTORY, FILE_SHARE_READ | FILE_SHARE_DELETE, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
FILE_NOTIFY_INFORMATION Buffer[1024];
DWORD BytesReturned;
int i = 0;
if (ReadDirectoryChangesW(hDir, &Buffer, sizeof(Buffer), TRUE, FILE_NOTIFY_CHANGE_CREATION | FILE_NOTIFY_CHANGE_LAST_WRITE | FILE_NOTIFY_CHANGE_SIZE
| FILE_NOTIFY_CHANGE_DIR_NAME | FILE_NOTIFY_CHANGE_FILE_NAME, &BytesReturned, NULL, NULL)) {
for (i = 0; i < BytesReturned; i++) {
if (Buffer.FileNameLength > 0) {
char* action = "_default_";
switch (Buffer.Action) {
case FILE_ACTION_ADDED:
action = "added";
break;
case FILE_ACTION_REMOVED:
action = "removed";
break;
case FILE_ACTION_MODIFIED:
action = "modified";
break;
case FILE_ACTION_RENAMED_OLD_NAME:
action = "renamed_old_name";
break;
case FILE_ACTION_RENAMED_NEW_NAME:
action = "renamed_new_name";
break;
case FILE_ACTION_ADDED_STREAM:
action = "ADDED_STREAM";
break;
case FILE_ACTION_ID_NOT_TUNNELLED:
action = "ID_NOT_TUNNELLED";
break;
case FILE_ACTION_MODIFIED_STREAM:
action = "MODIFIED_STREAM";
break;
case FILE_ACTION_REMOVED_BY_DELETE:
action = "REMOVED_BY_DELETE";
break;
case FILE_ACTION_REMOVED_STREAM:
action = "REMOVED_STREAM";
break;
case FILE_ACTION_TUNNELLED_ID_COLLISION:
action = "TUNNELLED_ID_COLLISION";
break;
}
char path[MAX_PATH];
WideCharToMultiByte(CP_ACP, 0, Buffer.FileName, Buffer.FileNameLength, path, sizeof(path), NULL, FALSE);
printf("%s:%s", action, path);
break;
}
}
}
return EXIT_SUCCESS;
}

os.popen("FileSystemChangeListener.exe %s" % self.path).read()